*Enzymes in Replication

Question 1

DNA gyrase

Answer 1

Type II topoisomerase, unwinds supercoils ahead of replication fork. (Comb)

Question 2

DNA ligase

Answer 2

Joins okazaki fragments into a continuous strand

Question 3

Primase

Answer 3

Initiates of DNA synthesis (leading and lagging strands). Constructs a short primer composed of RNA.

Question 4

Helicase

Answer 4

Unwind a DNA duplex in a reaction that uses energy released by ATP hydrolysis to move along 1 strand, breaking the H bonds

Question 5

Single-stranded DNA binding proteins (SSB proteins)

Answer 5

Bind to separated DNA strands, keeping it in extended state and preventing it from becoming rewound or damaged.

Question 6

Topoisomerase

Answer 6

Cuts DNA backbones to remove knots and other entanglements.

Question 7

DNA polymerase III

Answer 7

Major enzyme responsible for replication, adds 30,000 nucleotides/minute, but there are only 10 of them per cell.

Question 8

DNA polymerase I

Answer 8

Removes RNA primer on lagging strand. 5’ - 3’ and 3’ to 5’ exonuclease.

Question 9

DNA glycosylases

Answer 9

Recognizes a nucleotide alteration and initiates Base Excision Repair. Removes the base by cleaving the glycosidic bond.